Invasive plant spreading along coastal dunes

Lyme grass competes with other grasses.

Lyme grass competes with other grasses.

January 08, 2009

MUSKEGON, Mich. (AP) -- Lyme grass, an invasive plant that competes with native dune grass, is showing up along the Lake Michigan coast. A report prepared for The Nature Conservancy says lyme grass is flourishing at 125 coastal dune sites in Muskegon, Ottawa and Allegan counties. Botanists say the plant competes with native marram grass, or dune grass -- one of the predominant species in the Great Lakes coastal dunes. Lyme grass has the potential to spread and displace all native dune grasses, causing subtle but significant changes in plant, insect and animal communities. "There are many more occurrences of lyme grass than we want to see along this stretch of coastline ... but it's early enough in the infestation that we can do something about it," John Legge, West Michigan conservation director for The Nature Conservancy's Michigan chapter, told The Muskegon Chronicle for a recent report. Lyme grass is far more prevalent in the coastal dunes in Indiana and Wisconsin, the newspaper reported. The plant is native to the sandy coasts of Europe. It is one of 900 non-native plants in Michigan but the only one known to compete directly with marram grass for survival in the Great Lakes dunes. Lyme grass is one of at least 13 invasive species of plants and trees living in coastal dunes in Muskegon, Ottawa and Allegan counties, said William Martinus, who conducted the plant survey for The Nature Conservancy. The survey of 75 miles of dunes in western Michigan last summer found lyme grass growing at 17 sites in Muskegon County, 65 in Ottawa County and 43 in Allegan County. The plants resemble dune grass but have thick, blue-green blades and rigid seed stalks. Herbicide spraying can control the spread of lyme grass. But it's risky because the chemical that kills lyme grass has the same effect on native dune grass, Martinus said. Still, it's nearly impossible to eliminate lyme grass without herbicides. "In most instances, removal of (lyme) grass is only temporary, as it will usually regenerate from nearby rootstock," Martinus said in the report. Legge said efforts to remove lyme grass from area dunes could begin as early as next summer. He said the foreign plants must be removed soon to keep them from spreading and becoming the dominant species. Another troublesome invader, tall baby's breath, was found in the Kitchel-Lindquist Dune Preserve in Grand Haven, Mich. That plant species has colonized vast areas of dunes at the Sleeping Bear Dunes National Lakeshore near Traverse City, Mich. The federal government has spent thousands of dollars trying to control its spread.